Plasma levels of cortisol and opioid peptide beta-endorphin during spontaneous vaginal delivery

INTRODUCTION Labor pain is very frequent in clinical practice, but the underlying mechanisms as well as numerous neuroendocrine responses activated by such pain have not been fully explained yet. OBJECTIVE The objective of the study was to determine the influence of labor pain on plasma levels of cortisol and opioid peptide ß-endorphin. METHOD Cortisol and ß-endorphin levels were measured in blood plasma of: health, non-pregnant women (group 1, n=8), health pregnant women (group 2, n=8) and in parturitions, through fourth ages (group 3, n=8), Plasma level of cortisol was measured by radioimmunoassay, and ß-endorphin by enzyme immunoassay. Data were expressed as mean ± standard error of mean and were analyzed by Student's t test and Mann Whitney test. RESULTS Plasma level of cortisol in group 2 was significantly increased compared to the group 1. During labor progression, plasma level of cortisol was rising till the third labor age. Plasma level of cortisol in fourth labor age was not significantly different from the ag.e one and group 1. Plasma level of ß-endorphin was (n.g/L): in group 1:64±20, group 2:70±22, group 3:the first labor age: 75±15, the second labor age: 193±54, the third labor age: 346+97 and the fourth labor age: 114±31. CONCLUSION These results indicate that both ß-endorphin and cortisol are involved in regulation and modulation of labor pain and stress